1. Field of the Invention
This invention relates to a backhoe with an upper structure mounted on a traveling device through a bearing to be rotatable about a vertical axis, the upper structure supporting a cab having a side entrance opening with a door which swings open and close about a vertical pivotal axis.
2. Description of the Related Art
Attempts have been made to restrict such a door protruding from the cab, as disclosed in Japanese Patent Laying-Open Publication H8-291538 and Patent Laying-Open Publication H11-100864, for example. In the prior art disclosed in the former, an opening formed laterally of a cab has a door (entrance door) curved to follow a lateral profile of the cab and supported to be slidable in the fore and aft direction along the outer surface of the cab. The opening is opened by sliding the door rearward without protruding the door from the cab. In the prior art disclosed in the latter publication, a first door panel and a second door panel are interconnected to be pivotable relative to each other, and each panel is biased by a gas damper. When the door is opened, the first and second door panels follow the outer surface of the cab and protrude only a small amount from the outer surface.
Take a small swivel type backhoe for example, such a backhoe includes an upper structure designed such that, when rotated, its rear end does not protrude from the width of right and left crawlers. Consequently, when this type of backhoe is moved into a back alley to engage in an operation, for example, the upper structure is kept out of contact with objects such as a utility pole and part of a building present close to the right or left crawler. Where the cab on the upper structure has a door, the backhoe is designed on the assumption that the upper structure is rotated with the door closed. Thus, when the door is opened to a limit of its swinging movement (hereinafter referred to as a fully open position), the rear end of the door protrudes rearwardly from the upper structure. When the upper structure is rotated in this state, the end of the door could contact a utility pole or eaves of a house.
It is conceivable to eliminate the inconvenience of the free end of the opened door (which is at the forward end of the cab when closed) protruding rearwardly of the upper structure, by providing the door constructions disclosed in the two prior publications noted above. However, each of these prior constructions has a large number of parts, and is complicated, tending to increase cost. In addition, each of the prior constructions includes numerous actuating parts. There is room for improvement in that malfunctioning could easily occur.
The object of this invention is to provide an improved backhoe in which the free end of a door in a fully opened position does not protrude from the rear end of an upper structure.
The above object is fulfilled, according to this invention, by a backhoe as noted hereinbefore wherein an open/close axis of hinges is disposed in a rearward position of the opening and forwardly of a rear end of the door, and the door is swung about the open/close axis by moving a front end of the door outwardly of the cab.
In the above feature, the open/close axis is disposed forwardly of the rear end of the door in the closed position. Compared with a construction having the open/close axis disposed at or rearwardly of the rear end of the door in the closed position, the free end of the door (i.e. the front end of the door in the closed position) may be displaced forwardly when the door is placed in the fully open position. Further, this feature realizes a simple support structure for allowing the door to swing open and close about the open/close axis. There is no need to employ a complicated structure as discussed hereinbefore in relation to the prior art. Thus, an improved backhoe is provided, which has a reduced chance of malfunctioning, avoids cost increases, and avoids the inconvenience of the door protruding rearward from the rear end of the upper structure.
In an embodiment of this invention, the door has a front end in the closed position directed rearwardly of the cab when the door is in the fully open position, the front end of the door being contained in a region of rotation described by the upper structure rotating about the swivel axis.
In the above feature, the front end of the door is contained in the region of rotation of the upper structure even when the door is set to the fully open position. The door will not contact a utility pole or part of a house even when the upper structure is rotated with the door set to the fully open position. As a result, when the backhoe engages in an operation with the door set to the fully open position, smooth swivels may be made without damaging the door, utility pole and so on.
In the embodiment of this invention, each of the hinges includes a leaf connected to the opening, a leaf connected to the door, and a pin for interconnecting the leaves to be pivotable relative to each other about the axis, the leaves being bent to place the pin forwardly of the rear end of the door.
With the above feature, the simple improvement consisting in bending the leaves constituting each hinge not only places the open/close axis of the door forwardly of the rear end of the door, but requires little improvement to be made in the cab or door. As a result, the construction is easy to manufacture and a further cost reduction is achieved.
In the embodiment of this invention, the upper structure or the cab defines a recess opposed to the door and receiving part of the door when the door is set to the fully open position.
The above feature allows the door in the fully open position to lie along the upper structure or cab, with part of the door entering the recess in the upper structure or cab. Compared with a construction having no such recess, the door may be swung to a large extent. This increases the effect of avoiding the inconvenience of the door protruding from the upper structure or cab.
Other features and advantages of this invention will be apparent from the following description of the embodiments to be taken with reference to the drawings.